UniMoG Tech Tips

Since taking delivery of our 1963 Swiss 404 in December of 2000, we have learned much.  Mainly that they are much like Volkswagens except that the required tools are MUCH larger and take MUCH effort just to lug them around.  We were disappointed in the quality of the Mercedes UNIMOG workshop manual.  It's not as complete as the Robert Bentley manuals.  Therefore, we have decided that as we perform component and system level overhauls, we will share what we learn with others.  With the exception of Tip #1, the material here will be applicable to the 404.114 model and other similar variants.

Tip #1 - Manuals
Buy the Mercedes UNIMOG Instruction manual.  This small book is invaluable for simple things like 'what does that lever do?', 'where are all the lubrication points?', and the ever famous 'what torque do I tighten the wheel nuts too?'. It's also a good example of a fine manual.  It doesn't cover any of the overhaul procedures but everything you need to keep it in great shape.  My favorite section of the 404 Instruction manual are 2.3.6 and 3.3.4.

Tip #2 - Fuel Pumps
We have replaced the stock mechanical fuel pump with two 24V electric fuel pumps.  For details of our setup and how we diagnosed the problem, click here

Tip #3 - Rant on Oil
Use Synthetic!

Click here to read our in-depth rant on our findings and what oils we're using in our engine & transmission.

Tip #4 - Transmission Temperature
Since we put over 30,000km on our truck in less than the first 3 years of ownership, 12,000 or so of those on our new transmission, we have made a lot of careful observations about transmission temperature.

Tip #5 - Hazard Lights
The Swiss 404 did not come equipped with a 4-way flasher, this is one solution to that problem.

Tip #6 - 404 Oil filter leaking? Is your 404 engine oil filter leaking?  Check carefully to see if yours has the same problem that ours had when we got it.  At some point while changing the oil filter, someone hadn't removed the old O-ring from the filter housing before installing the new one.  Having two O-rings in there does not help it seal or seat!  Once we peeled two O-rings out and replaced them with ONE new one, we have had no engine oil leaks.  (Hardly a German truck any more since it doesn't mark it's spot!)

Tip #7 - Gearshift rattling?
One of the benefits of replacing our transmission was getting a new gearshift that didn't rattle like the old one.  You might be able to use our idea for solving your rattly gearshift without spending quite so much time and money.

Tip #8 - Reverse Light Switch.
There are times when it is convenient to have automatic back-up lights.  Click here to see how we made ours work.

Tip #9 - Part Numbers.
We have successfully ordered some parts from our local Mercedes Benz car dealer.  A number of tune up parts are also available from your local auto parts store, once you convince them to look up the part numbers correctly.  Click here for a list of current part numbers.

Tip #10 - Tires.
With over three seasons, 38,000+ km, and one flat on our first set of Continental MPT 81's, we have some observations

Tip #11 - 12 Volt tach. installation.
In the standard 24V 404, it is rather easy to install a 12 V tach.  The negative side of the ballast resistor is the positive side of the coil, which sees about the same voltage as the positive side of the coil on a 12 V vehicle which uses a coil with internal resistance (like a VW).  Don't forget to give your instrument light in the tach 12 V instead of 24!!!

Tip #12 - Tools.
It is easy to carry all the necessary tools in the stock 404 tool box if you make tool rolls out of old jeans to wrap them in.

Tip #13 – Engine Replacement Checklists.
Since we had our cab off twice in less than six months, to make the second time (when we had to replace the engine) go more quickly, we made very detailed lists of what we needed on hand & what we needed to do.  Recognizing that some items will differ from one 404 to the next, feel free to make use of our checklists they may make the job go a little more smoothly for you!